Overview
EN ISO 19901-4:2025 - Geotechnical design considerations provides consolidated requirements and guidance for geotechnical engineering of offshore structures used in oil, gas and lower carbon energy industries. Endorsed by CEN and issued as ISO 19901-4:2025, this standard supersedes EN ISO 19901-4:2016 and targets a wide range of offshore foundation types rather than a single structure class.
The standard addresses shallow, intermediate and long/flexible pile foundations using the commonly accepted geometric classification:
- Shallow foundations: embedded length/diameter ratio L/D < 0.5
- Intermediate foundations: 0.5 ≤ L/D ≤ 10
- Long/flexible piles: L/D > 10
Key Topics
- Site investigation and geohazard identification: guidance on geological modelling, soil sampling, testing, and recognising carbonate soils and other hazards.
- Soil-structure interaction: methods for flowlines, risers, conductors and auxiliary subsea structures.
- Foundation design principles: acceptance criteria, representative and design values of soil parameters, partial factors and reliability-based design approaches.
- Shallow & intermediate foundations: bearing capacity, sliding, serviceability (displacements/rotations), hydraulic stability, and installation aspects such as skirt penetration.
- Pile foundations: axial and lateral capacity, dynamic/cyclic response and design methods for long, flexible piles.
- Anchors and station-keeping: design considerations for anchors used with floating facilities.
- Testing, instrumentation and monitoring: requirements for in-situ and laboratory testing and performance monitoring during and after installation.
- Installation, relocation and removal: practical guidance on installation loads, under-pressure control and retrieval.
Applications
This standard is intended for practical offshore foundation design, assessment and verification across:
- Fixed platforms, jackets and gravity-based structures
- Floating facilities requiring anchor design and station-keeping
- Subsea infrastructure: flowlines, risers, conductors and seabed supports
- Lower carbon energy installations (wind, tidal, hybrid offshore systems)
Use EN ISO 19901-4:2025 for design basis development, engineering specifications, tender documents, and verification of geotechnical risk and performance.
Who should use it
- Offshore geotechnical and geoscience engineers
- Structural and foundation design engineers for offshore projects
- Project managers, owners and operators in oil, gas and lower carbon energy sectors
- Contractors, inspection bodies and regulatory authorities involved in foundation design, installation and monitoring
Related standards
- ISO 19901 series (other parts covering metocean, subsea, topsides aspects)
- Applicable national and CEN-adopted offshore standards and codes for structural and load design
EN ISO 19901-4:2025 is a key reference for consistent, risk-informed offshore foundation design and soil-structure interaction assessment.
